Aqueous coating compositions

ABSTRACT

The present invention relates to a dispersant composition comprising at least one non-ionic surfactant and at least one polymer comprising at least one salt of a carboxylic acid group. Also disclosed are pigment compositions and aqueous coating compositions comprising the dispersant composition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dispersant composition comprising atleast one non-ionic surfactant and at least one polymer comprising atleast one salt of a carboxylic acid group. The present invention furtherrelates to a modified pigment composition and an aqueous coatingcomposition comprising the dispersant compositions.

2. Description of the Related Art

Coating compositions are used for decorative, protective, and functionaltreatments of many kinds of surfaces. These surfaces include coils,metals, appliances, furniture, hardboard, lumber and plywood, marine,automobile, cans, and paperboard. Some coatings, such as those onundersea pipelines, are for protective purposes. Others, such asexterior automobile coatings, fulfill both decorative and protectivefunctions. Still others provide friction control on boat decks or carseats. Some coatings control the fouling of ship bottoms, others protectfood and beverages in cans. Silicon chips, printed circuit panels,coatings on wave-guide fibers for signal transmission, and magneticcoatings on videotapes and computer disks are among many so-calledhi-tech applications for coatings.

Surface coating compositions are generally more or less viscous liquidswith three base components: a film-forming substance or combination ofsubstances called the resin or binder, a pigment or combination ofpigments, and a volatile liquid. The combination of resin and volatileliquid is often referred to as the vehicle. Vehicles may be aqueous ornon-aqueous and may be in a solution form or as a dispersion of finebinder particles in a non-solvent. The components and manufacturing ofcoating compositions such as aqueous coatings are further discussed inthe Concise Encyclopedia of Polymers, Science and Engineering, pages.160-171 (1990), which is incorporated herein by reference.

Pigments are finely divided, insoluble, solid particles dispersed in thecoating vehicle and are distributed throughout the resin or binder inthe final film. A wide variety of conventional black and coloredpigments have been used in coating compositions. In addition, aqueousand non-aqueous inks and coating compositions comprising modified carbonproducts having attached organic groups are described in U.S. Pat. Nos.5,672,198 and 5,713,988, both incorporated in their entireties herein byreference.

Surfactants may also be added to coating compositions to help improveperformance. Typically, these surfactants are used in combination withthe pigments of the coating compositions and, as such, are thereforereferred to as dispersants. Several different classes or types ofdispersants have been used in coating compositions. The choice ofdispersant is dependent on a variety of factors, including theproperties of the pigment, particle size, and the type of resin orbinder. However, the dispersant can often have a negative impact onproperties such as color development. Therefore, the amount ofdispersant must be adjusted for the components used in order to obtaincoating compositions with good overall properties.

Thus, while dispersants have been used in coating compositions, thereremains a need for dispersant compositions which enable specific typesof pigments to be dispersed in an aqueous vehicle while also resultingin good color performance.

SUMMARY OF THE INVENTION

The present invention relates to a dispersant composition comprising i)at least one non-ionic surfactant and ii) at least one polymercomprising at least one salt of a carboxylic acid group. Preferably, thenon-ionic surfactant is insoluble in water, such as a water insolublepolyalkylene oxide.

The present invention further relates to a pigment compositioncomprising a) at least one pigment, and b) at least one dispersantcomposition as described herein. Preferably the pigment is a modifiedcarbon product comprising a carbon product having attached at least oneorganic group such as an anionic group. The pigment composition may beeither in a dry form or present in an aqueous vehicle.

The present invention further relates to an aqueous coating compositioncomprising a) an aqueous vehicle comprising a water-based resin and anaqueous solvent, b) at least one pigment, and c) at least one dispersantcomposition as described herein.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to dispersant compositions, as well as topigment and aqueous coating compositions comprising the dispersantcompositions.

The dispersant composition of the present invention comprises at leastone non-ionic surfactant and at least one polymer comprising at leastone salt of a carboxylic acid group. Additionally, the dispersantcomposition may further comprise a solvent. The solvent may be aqueousor non-aqueous, but is preferably an aqueous solvent—i.e., the solventcomprises water and, optionally, water soluble or miscible solvents.Preferably, the solvent is water, and the dispersant composition is awater-based dispersant composition.

Preferably, the non-ionic surfactant is a polyalkylene oxide. Thepolyalkylene oxide can be any homopolymer or copolymer comprising analkylene oxide group, such as an ethylene oxide or propylene oxidegroup. The polymer may also be a branched or linear polymer. Preferably,the polyalkylene oxide is a polymer comprising alkylene oxide groupshaving from 1 to 12 carbons. For example, the polyalkylene oxide may bea polymer comprising a —CH₂—CH₂—O— group, a —CH(CH₃)—CH₂—O— group, a—CH₂—CH(CH₃)—O— group, or a —CH₂—CH₂—CH₂—O— group. Combinations of thesegroups are also possible. In addition, mixtures of polyalkylene oxidesmay also be used.

Typically, polyalkylene oxide polymers are prepared so as to containterminal —OH groups. These terminal groups can be further reacted orcapped to form polymers having —OR groups. Examples of capping groupsare well known to one skilled in the art. The polyalkylene oxide used inthe dispersant composition of the present invention may be either anuncapped or a capped polymer. Preferably, for the solubility reasonsdiscussed in more detail below, the polyalkylene oxide polymer comprisesa capping group. The percentage of —OH groups that are capped can be anyamount. Preferably, the polyalkylene oxide is greater than 50% capped,more preferably greater than 75% capped, and most preferably greaterthan 90% capped. The capping group can be any of those known in the artbut is preferably a C1-C20 alkyl or aryl group, more preferably a C6-C20alkyl group. Most preferred is a C12-C18 alkyl group.

The dispersant composition of the present invention further comprises atleast one polymer comprising at least one salt of a carboxylic acidgroup. Examples include homo- or copolymers prepared from acrylic ormethacrylic acid and polyesters, polyamides, or polycarbonates thatcontain —COOH end-groups. Preferably, the polymer is a copolymer ofacrylic or methacrylic acid and the polymer comprises at least one saltof an acrylic or methacrylic acid repeat group.

The salt may be either an inorganic or an organic salt. Thus, the saltof a carboxylic acid group has the general formula —COO⁻M⁺, wherein M⁺can be either an inorganic counterion or an organic counterion. Examplesinclude Na⁺, K⁺, Li⁺, NH₄ ⁺, and NR′₄ ⁺, where R′ represents hydrogen oran organic group such as a substituted or unsubstituted aryl and/oralkyl group. Preferably the polymer comprises an ammonium salt of acarboxylic acid group.

Molecular weight determines many properties of both surfactants andpolymers, including solubility, viscosity, and stability. Therefore,while the non-ionic surfactant and polymer used in the dispersantcomposition of the present invention can have any molecular weight,generally, very high molecular weights are not preferred. Thus, themolecular weight of the non-ionic surfactant such as a polyalkyleneoxide is preferred to be between about 500 and 200000, more preferablyabout 1000 to 100000, and most preferably between about 2500 and 10000.The molecular weight of the carboxylic acid group-containing polymer maybe similar to that described for the non-ionic surfactant. Preferably,the polymer molecular weight is between about 500 and 100000, morepreferably between about 5000 and 50000, and most preferably betweenabout 10000 and 40000.

The dispersant composition, may further comprise additional components,such as antioxidants, biocides, and the like. As described above, in apreferred embodiment, the dispersant composition further comprises anaqueous solvent, such as water. Furthermore, the pH of the compositioncan be adjusted depending on the intended use of the material. Thus, thedispersant composition may further comprise at least one base. This basemay correspond to the salt of the polymer comprising at least one saltof a carboxylic acid. Examples of bases include amines such as ammoniaand hydroxide reagents such as a salt having an hydroxide counterionincluding, but not limited to, sodium hydroxide, potassium hydroxide,lithium hydroxide, and ammonium hydroxide. Other hydroxide salts, aswell as mixtures of hydroxide reagents, can also be used. Furthermore,other alkaline reagents may also be used which generate OH⁻ ions in anaqueous medium. Examples include carbonates such as sodium carbonate,bicarbonates such as sodium bicarbonate, and alkoxides such as sodiummethoxide and sodium ethoxide.

The amount of each component can be varied depending on the intended useof the dispersant composition. The amount of non-ionic surfactant istypically between about 5% and 20%, preferably between about 9% and 16%,and more preferably between about 11% and 14%, based on the total weightof the dispersant composition. The amount of polymer comprising at leastone salt of a carboxylic acid group is generally between about 3% and25%, preferably between about 7% and 20%, and more preferably betweenabout 10% and 15%, based on the total weight of the dispersantcomposition.

As described above, preferably the dispersant composition furthercomprises an aqueous solvent, such as water. For this preferredembodiment, the % solids of the dispersant composition is preferablygreater than 10%, more preferably greater than 15%, and most preferablygreater than 25%.

It is preferable that at least one of the components of the dispersantcomposition be insoluble in water. For example, the non-ionic surfactantmay be a water insoluble material. By “insoluble” is meant that at leastone of the components does not dissolve in water at room temperature atconcentrations greater than 2% and remain soluble under these conditionsfor a long period of time, such as longer than a day. Insolubility maybe a result of many different factors. For example, when the non-ionicsurfactant is a polyalkylene oxide, insolubility may be a result of themolecular weight of the polyalkylene oxide, the type of alkylene oxidewhich comprises the polymer, or the type and level of capping groups.When the non-ionic surfactant is insoluble in water, the polymercomprising at least one salt of carboxylic acid group should be watersoluble. Thus, it may be said that the polymer acts as a dispersing orsolubilizing agent for the water-insoluble non-ionic surfactant, therebyproducing an aqueous solution or dispersion of the insoluble surfactant.

The present invention further relates to a pigment compositioncomprising at least one pigment and the dispersant composition describedabove. The pigment may be any pigment known in the art but is preferablya carbonaceous pigment, and, in particular, is a carbon product.Examples of suitable carbon products include, but are not limited to,graphite, carbon black, vitreous carbon, carbon fibers, activatedcharcoal, and activated carbon. The carbon may be of the crystalline oramorphous type. Finely divided forms of the above are preferred; also,it is possible to utilize mixtures of different carbons. Of these carbonproducts, carbon black is preferred. The pigment composition may beeither in a dry form or may further comprise an aqueous vehicle such aswater. Thus, the pigment composition may be an aqueous dispersion of apigment and the dispersant composition described above.

Pigments are often categorized by their color strength. For example,carbon blacks may be referred to as high color blacks, medium colorblacks, or regular color blacks. Any of these carbon blacks can be usedfor the pigment composition of the present invention. In a preferredembodiment, the pigment composition comprises carbon products referredto in the art as high color blacks which generally have BET surface areavalues greater than or equal to about 240 m²/g. Preferably, the highcolor carbon blacks used in the pigment composition of the presentinvention have a BET surface area values greater than or equal to about300 m²/g, more preferably greater than or equal to about 400 m²/g, andmost preferably greater than or equal to about 500 m²/g. Examples ofhigh color blacks include, but are not limited to Monarch® 1000,Monarch® 11100, Monarch® 1300, Monarch® 1400, Monarch® 1500, BlackPearls® 1000, Black Pearls® 1100, Black Pearls® 1300, and Black Pearls®1400.

These so-called high color carbon black also further have defined DBPA(dibutyl phthalate absorption) values. DBPA is a measure of thestructure or branching of the carbon product. The greater the structure,in general, the better the dispersibility of the carbon product in, forexample, a coating composition. However, the greater the structure, thehigher the viscosity of the coating composition. Also, higher structuregenerally results in poorer color performance—lower gloss and jetness.Thus, preferred high color carbon blacks will have DBPA values betweenabout 50 and 150 cc/100 g. Most preferred are those that further have aDBPA value between about 50 and 100 cc/100 g.

In another preferred embodiment, the pigment composition of the presentinvention comprises carbon products referred to in the art as mediumcolor blacks and generally have BET surface area values between about150 m²/g and 240 m²/g. Preferably, the medium color carbon blacks usedin the pigment composition of the present invention have BET surfacearea values between about 170 and 240 m²/g and more preferably betweenabout 200 and 230 m²/g. The medium color blacks further have DBPA valuesbetween about 50 and 150 cc/100 g. Most preferred are those that furtherhave a DBPA value between about 60 and 130 cc/100 g. Examples of mediumcolor blacks include, but are not limited to, Monarch® 700, Monarch®800, Monarch® 880, Monarch® 900, Black Pearls® 700, Black Pearls® 800,Black Pearls® 880, and Black Pearls® 900.

In another embodiment, the pigment composition of the present inventioncomprises carbon blacks that have been oxidized in order to increase theamount of oxygen functionality on the surface. Oxidized carbon blacksare well known in the art and are typically prepared by the reaction ofan oxidant, such as nitric acid or ozone, with a base carbon black. Theincrease in functionality on the surface typically gives rise to adecrease in pH. Thus, oxidized carbon blacks are typically acidic.

In another embodiment, the pigment composition of the present inventioncomprises a modified pigment having attached at least one organic group.Preferably, the modified pigment is a modified carbon product. Themodified carbon product may have BET surface area values between about350 and 600 m²/g, and more preferably between about 350 and 500 m²/g.While any modified carbon product with BET surface area values greaterthan or equal to 350 m²/g can be used in the pigment composition of thepresent invention, preferred are those which further have DBPA valuesbetween about 60 and 150 cc/100 g. Most preferred are those that furtherhave a DBPA value between 80 and 120 cc/100 g.

The modified carbon products are prepared using methods known to thoseskilled in the art such that chemical groups (e.g., polymeric andorganic) are attached to the pigment, providing a more stable attachmentof the groups onto the pigment compared to adsorbed groups, e.g.,polymers, surfactants, and the like. For example, the modified carbonproducts can be prepared using the methods described in U.S. Pat. Nos.5,554,739, 5,851,280, 6,042,643, 5,707,432, and 5,837,045, and PCTPublication WO 99/23174, the descriptions of which are fullyincorporated herein by reference. The modified carbon products can beprepared from any of the carbon products described above. Preferably,the carbon product is either carbon black or an oxidized carbon black.

The attached organic group is chosen depending on a variety of factors,including the specific components of the dispersant composition as wellas the intend use of the pigment composition. This allows for greaterflexibility by tailoring the modified carbon product to the specificapplication. The organic group may comprise an ionic group, an ionizablegroup, or a mixture of an ionic group and an ionizable group. An ionicgroup is either anionic or cationic and is associated with a counterionof the opposite charge including inorganic or organic counterions suchas Na⁺, K⁺, Li⁺, NH₄ ⁺, NR′₄ ⁺ acetate, NO₃ ⁻, SO₄ ⁻², OH⁻, and Cl⁻,where R′ represents hydrogen or an organic group such as a substitutedor unsubstituted aryl and/or alkyl group. An ionizable group is one thatis capable of forming an ionic group in the medium of use. Thus,preferably the organic group is an organic ionic group. Organic ionicgroups include those described in U.S. Pat. No. 5,698,016, thedescription of which is fully incorporated herein by reference.

Preferably, the organic group comprises at least one anionic group,which is a negatively charged ionic group. Anionic groups may begenerated from groups having ionizable substituents that can formanions, such as acidic substituents, or may be the anion in the salts ofionizable substituents. Preferably, when the ionizable substituent formsan anion, the ionizable substituent has a pKa of less than 11. Theorganic ionic group could further be generated from a species havingionizable groups with a pKa of less than 11 and salts of ionizablesubstituents having a pKa of less than 11. The pKa of the ionizablesubstituent refers to the pKa of the ionizable substituent as a whole,not just the acidic substituent. More preferably, the pKa is less than10 and most preferably less than 9.

Representative examples of ionic groups include —COO⁻, —SO₃ ⁻, —HPO₃ ⁻,and —PO₃ ⁻². Representative examples of ionizable groups include —COOH,—SO₃H —PO₃H₂, —SO₂NH₂, and —SO₂NHCOR′, where R′ represents hydrogen oran organic group such as a substituted or unsubstituted aryl and/oralkyl group. Particularly preferred species are —COO⁻ and —SO₃ ⁻.Preferably, the organic ionic group is generated from a substituted orunsubstituted carboxyphenyl group or a substituted or unsubstitutedsulfophenyl group. Specific organic ionic groups are —C₆H₄CO₂ ⁻ and—C₆H₄SO₃ ⁻.

Attached groups comprising ionic or ionizable groups are most preferredwhen the pigment composition further comprises an aqueous vehicle. Inaddition, these charged groups are also preferred when the pigmentcomposition is used in an aqueous coating composition, as is describedbelow. Under these conditions, the attached groups can provide increasedstability of the carbon product in the vehicle.

The amount of attached groups can be varied depending on the intendeduse of the pigment composition. For example, the amount of attachedorganic groups on the modified carbon products is chosen in order toobtain the desired performance the pigment composition in the coatingcompositions of the present invention. In general, the amount ofattached organic groups is from about 0.001 to about 10.0 micromoles oforganic group per m² surface area of pigment (surface area as measuredby nitrogen adsorption, and, in particular, the t-area method).Preferably, the amount of attached organic groups is between from about0.1 to about 5.0 micromoles per m², and most preferably the amount ofattached organic groups is between from about 0.1 to about 2.7micromoles per m 2. The amount attached can be varied depending on thespecific attached group and can be adjusted depending on, for example,the size of the attached group or the functionality of the ionic group.Further, it is also within the scope of the present invention to havemore than one type of attached group on the carbon product in order toprovide for the best overall performance.

The modified carbon products may be purified by washing, such as byfiltration, centrifugation, or a combination of the two methods, toremove unreacted raw materials, byproduct salts and other reactionimpurities. The products may also be isolated, for example, byevaporation or it may be recovered by filtration and drying using knowntechniques to those skilled in the art. Dispersions of the modifiedcarbon products may be further purified or classified to removeimpurities and other undesirable free species which can co-exist in thedispersion as a result of the manufacturing process. For example, adispersion of the modified carbon product can be subjected to aclassification step, such as centrifugation, to substantially removeparticles having a size above about 1.0 micron. In addition, thedispersion can be purified to remove any undesired free species, such asunreacted treating agent. Known techniques ofultrafiltration/diafiltration using a membrane or ion exchange may beused to purify the dispersion and remove a substantial amount of freeionic and unwanted species. Also, an optional exchange of counterionswhereby the counterions that form a part of the modified carbon productscan be exchanged or substituted with alternative counterions (including,e.g., amphiphilic ions) utilizing known ion exchange techniques such asultrafiltration, reverse osmosis, ion exchange columns and the like.Particular examples of counterions that can be exchanged include, butare not limited to, Na⁺, K⁺, Li⁺, NH₄ ⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃ ⁻, NO₂ ⁻,acetate, and Br⁻. The removal of impurities from the modified carbonproducts may also improve the performance of the pigment compositions,in particular, in the coating compositions described below.

The pigment compositions may be prepared by any method known to oneskilled in the art. In particular, the components may be added in anyorder. For example, for a pigment composition comprising a modifiedcarbon product, the dispersant composition may either be added to themodified carbon product or vice versa. Also, the dispersant compositionmay be added anywhere along the process of preparing and isolating thepigment. For example, for a pigment composition comprising a modifiedcarbon product, the dispersant composition may be added either prior toor after a pelletizing step (or other steps for changing the form of theproduct for improved handling), a drying step, or a pre-packing step.

The dispersant and pigment compositions of the present invention can beused in a variety of applications. Examples include inks, includinginkjet inks, coatings, adhesives, plastics, and sealants. In particular,the dispersant and pigment compositions described herein have been foundto be useful in aqueous coating applications.

Thus, the present invention relates to an aqueous coating compositioncomprising an aqueous vehicle, at least one pigment, and at least onedispersant composition. The pigment and dispersant composition are asdescribed above. The pigment can be any pigment described above but ispreferably a modified carbon product having attached at least oneorganic group, such as an anionic group.

In general, as discussed above, a coating composition comprises apigment dispersed in a solvent and a binder or resin (the vehicle). Thevehicle for the coating compositions of the present invention is anaqueous vehicle and comprises an aqueous solvent and a water-basedresin. The composition of the vehicle can vary depending on theconditions and requirements for the final coating. For example, theresin content can vary between about 70-100%.

As used herein, the term “water-based” refers to resins or binders thatcontain, or can contain, an aqueous solvent, such as water. Thus,water-based resins include latexes, water-borne or water soluble resins,and water-reducible resins. Examples of water-based resins or bindersuseful for the aqueous coating composition of the present inventioninclude, but are not limited to, acrylic resins, alkyd resins,polyurethane resins, epoxy resins, and vinyl-chloride-copolymer resins.The aqueous solvent can include water soluble solvents but is preferablywater. The content of the aqueous solvent may vary between nearly 0% and80%. Preferably the aqueous solvent comprises greater than 50% water,more preferably greater than 70% water, and most preferably greater than85% water.

The vehicle may also contain optional additives which can be used toimprove such properties as viscosity, leveling, and dry time. Examplesinclude cosolvents (in particular, water soluble solvents for aqueouscoatings), surfactants, and fillers such as clays, talcs, silicas, andcarbonates. Additionally, flow modifiers, leveling aids, and biocidescan be added.

The coating compositions of the present invention can be prepared usingany technique known to those skilled in the art. Thus, for example, thepigment can be combined with a liquid vehicle and other coatingcomponents in a high speed mixer and/or mill. The amount of carbonproduct used in the coating compositions of the present invention isdependent on the desired performance of the resulting coating. Ingeneral, these coating compositions comprise up to about 30% by weightpigment, such as a carbon product. The amount of carbon product can beadjusted in order to optimize such properties as jetness, viscosity, anddispersion stability.

The coating compositions of the present invention can be used in avariety of different end-use applications, such as, for example,automotive topcoats, to give coatings with improved overall performanceproperties. The pigment compositions of the present invention can bereadily dispersed in the coating compositions to obtain coatings withimproved jetness and bluetone. This will be further clarified by thefollowing examples, which are intended to be purely exemplary of thepresent invention.

EXAMPLES Example 1

This example describes the preparation of an exemplary dispersantcomposition of the present invention.

To a beaker placed on a hot plate set at 70° C. was added 100 g ofNeoCryl BT-24 (a waterborne acrylic resin available from Neoresins) inthe presence of 100 grams of water. Once the temperature reached 70° C.,50 g of Unithox 490 (a polyalkylene oxide surfactant available fromBaker Petrolite) was slowly added to the stirring solution. Afterapproximately 2 minutes of continuous stirring, a solution of 2.5 g ofin 200 grams of water is added. A clear solution was obtained. Themixture was stirred for another 30 minutes while maintaining thetemperature at approximately 70° C. 747.5 g of DI water is then added tothe mixture and stirred vigorously for another 5 minutes. The resultingdispersant composition was then used for the preparation of a pigmentcomposition, as described in more detail below.

Example 2

This examples describes the preparation of an exemplary pigmentcomposition of the present invention.

A pin pelletizer (10 horsepower) was heated to 70° C. 300 g of Emperor®2000 pigment black (a modified carbon black having attached —C₆H₄—SO₃Nagroups available from Cabot Corporation) was added to the pelletizerchamber and premixed at 400 rpm for 2 minutes. 60 g of the dispersantcomposition of Example 1 was also added to the chamber, and mixing wascontinued for another 10 minutes at 500 rpm. The resulting pigmentcomposition was then removed from the chamber, dried at 60-70° C. in anoven for 3 hours, and was used to prepare coating compositions, asdescribed in more detail below.

Example 3 and Comparative Examples 1-5

Example 3 demonstrates the preparation and analysis of an exemplarycoating composition of the present invention.

For this example and the comparative examples, the following procedurewas followed. A millbase was prepared by premixing 75.63 parts of waterwith 2.00 parts of Foamaster NX-1 (a defoamer available from Cognis) inthe presence of 8.87 parts of Dispersant D1441 (a surfactant availablefrom Baker Petrolite) in a high speed DisperMat mixer with goodagitation for 2-3 minutes. To this premix was added 13.5 parts of thedesired pigment (shown in Table 1 and Table 2 below) at 2000 rpm for 2minutes. Then the mixing speed was increased to 4,000 rpm for another 5minutes. The resulting mixture was then recirculated through an Eigermill at 10.0 m/s tip speed for 20 minutes at room temperature usingzirconium silicate beads (0.6-0.8 mm). The resulting millbase was thenused for the preparation of a coating composition.

A coating composition was prepared by mixing 12.0 parts of PnB solvent(available from Lyondell) with 18 parts of Cymel 325 melamine resin(available from Cytec) until a homogeneous solution was achieved. Themixture was added into 300 parts of waterborne polyurethane NeorezR-9624 (available from Neoresin) under good agitation and then mixed foranother 20 minutes under good agitation to produce a letdownmasterbatch. 71.6 parts of the millbase described above and 330 parts ofthe letdown masterbatch were mixed together for 15 minutes under goodagitation to produce the final coating composition.

A base coat was prepared by spraying out the coating composition ontocold roll steel. This was used for both a mono-coat system and a basecoat/clear coat system. For the mono-coat system, the panels wereflashed off at room temperature for 10 minutes and force dried at 150°C. for 20 minutes to cure. For the base coat/clear coat system, thepanels were flashed off at room temperature for 10 minutes, and forcedried at 120° C. for 10 minutes. Then a clear coat was applied on top(based on Macrynal 510, available from UCB). The panels were thenflashed off at room temperature for 10 minutes and then cured at 150° C.for another 20 minutes.

Properties of the resulting coatings were measured and are shown inTable 1 and Table 2 below. A Hunter Color Meter was used to measure L(jetness), a (red tone), and b (bluetone) values. A lower L value meansa greater level of jetness while the more negative a value for b, thebetter the bluetone. Mc is the color-dependent black value which can becalculated from L, a, and b. A higher Mc value also indicates a greaterlevel of jetness.

TABLE 1 Mono-coat Example # Comp. Comp. Comp. Comp. Ex. 3 1 2 3 4 Comp.5 Pigment* Ex 2 R5000 FW200 FW285 M1400 M1500 Base Coat 0.8-1.0 0.8-1.00.8-1.0 0.8-1.0 0.8-1.0 0.8-1.0 DFT (mils)* L 1.43 2.31 2.20 3.15 1.941.98 a −0.14 −0.14 −0.31 −0.53 −0.17 −0.12 b −0.92 0.03 −0.90 −0.41 0.220.20 Mc 295 260 272 251 265 264 *M1400 and M1500 are Monarch ® 1400carbon black and Monarch ® 1500 carbon black commercially available fromCabot Corporation. FW200 and FW285 are Color Black FW200 and Color BlackFW285 commercially available from Degussa-Huls Corporation. R5000 isRaven ® 5000 carbon black commercially available from Columbian ChemicalCompany

TABLE 2 Base coat/clear coat Example # Comp. Comp. Comp. Comp. Ex. 3 1 23 4 Comp. 5 Pigment Ex. 2 R5000 FW200 FW285 M1400 M1500 Base Coat0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 DFT (mils)* Base/Clear1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 Coat DFT (mils)* L 1.341.78 1.71 2.10 1.62 1.67 a −0.19 0.11 −0.15 −0.18 0.05 0.09 b −0.66 0.03−0.27 0.05 0.21 0.14 Mc 295 269 277 264 271 271

As can be seen from the results in Table 1 and Table 2, the coatingcomposition of Example 3 has a considerably higher Mc value along with amuch lower L value in both mono-coat and base coat/clear coat systems.In addition, bluetone is comparable or, in most cases, also improved.Thus, the dispersant compositions of the present invention can be usedto prepare pigment compositions which give coating composition with goodjetness and bluetone compared to coating compositions of the ComparativeExamples.

Example 4 and Comparative Examples 6-10

Example 4 demonstrates the preparation and analysis of an exemplarycoating composition of the present invention.

For this example and the comparative examples, a millbase was preparedusing a procedure similar to that of Example 3. 30.0 parts of a watergrind resin BT24 (available from Neoresins) was premixed with 57.5 partsof DI water in the presence of 3.0 parts of ammonia and 2.0 parts ofDehydran 1293 (defoamer available from Cognis) in a high speed DisperMatmixer with good agitation for 2-3 minutes. To this premix was added 7.5parts of the desired pigment (shown in Table 3 and Table 4 below) at2000 rpm for 2 minutes. Then the mixing speed was increased to 4,000 rpmfor another 5 minutes. The mixture was then recirculated through anEiger mill at 10.0 m/s tip speed for 20 minutes at room temperatureusing zirconium silicate beads (0.6-0.8 mm). The resulting millbase wasthen used for the preparation of a coating composition.

A coating composition was prepared by mixing 20 parts of PnB solvent and16 parts of DPnB solvent (both available from Lyondell) with 37.5 partsof Cymel 373 melamine resin (available from Cytec) until a homogeneoussolution was achieved. The mixture was added into 300 parts ofwaterborne acrylic latex Neocryl XK-100 (available from Neoresin) undergood agitation. Wetting agent BYK 346 (available from BYK Chemie) anddefoamer Dehydran 1293 (available from Cognis) were post added undergood agitation. The mixture was premixed for another 20 minutes undergood agitation to produce a letdown masterbatch. 10.0 parts of themillbase described above and 44.75 parts of the letdown masterbatch weremixed together for 15 minutes under good agitation to produce the finalcoating composition.

A base coat was prepared by spraying out the coating composition ontocold roll steel. This was used for both a mono-coat system and a basecoat/clear coat system. For the mono-coat system, the panels wereflashed off at room temperature for 10 minutes and force dried at 150°C. for 20 minutes to cure. For the base coat/clear coat system, thepanels were flashed off at room temperature for 10 minutes, and forcedried at 120° C. for 10 minutes. Then a clear coat was applied on toptop (based on Macrynal 510, available from UCB). The panels were thenflashed off at room temperature for 10 minutes and then cured at 150° C.for another 20 minutes.

Properties of the coating were measured and are shown in Table 3 andTable 4 below. A Hunter Color Meter was used to measure L (jetness), a(red tone), and b (bluetone) values. A lower L value means a greaterlevel of jetness while the more negative a value for b, the better thebluetone. Mc is the color-dependent black value which can be calculatedfrom L, a, and b. A higher Mc value also indicates a greater level ofjetness.

TABLE 3 Mono-coat Example # Comp. Comp. Comp. Comp. Ex. 4 6 7 8 9 Comp.10 Pigment Ex. 2 M1400 M1500 FW285 R5000 M1300 Base Coat 0.8-1.0 0.8-1.00.8-1.0 0.8-1.0 0.8-1.0 0.8-1.0 DFT (mils)* L .98 1.21 1.35 1.47 1.481.39 a −0.14 0.09 0.13 0.00 0.00 0.08 b −0.95 −0.41 −0.42 −0.42 −0.52−0.44 Mc 317 294 289 286 287 288 *M1300, M1400, and M1500 are Monarch ®1300 carbon black, Monarch ® 1400 carbon black, and Monarch ® 1500carbon black commercially available from Cabot Corporation. FW285 isColor Black FW285 commercially available from Degussa-Huls Corporation.R5000 is Raven ® 5000 carbon black commercially available from ColumbianChemical Company

TABLE 4 Base coat/clear coat Example # Comp. Comp. Comp. Comp. Ex. 4 6 78 9 Comp. 10 Pigment Ex. 2 M1400 M1500 FW285 R5000 M1300 Base Coat0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 DFT (mils)* Base/Clear1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 1.4-1.7 Coat DFT (mils)* L 1.171.21 1.29 1.46 1.40 1.45 a −0.02 0.04 0.00 0.05 −0.07 0.05 b −1.11 −0.69−0.23 −0.40 −0.25 −0.27 Mc 308 299 289 285 286 284

As can be seen from the results in Table 3 and Table 4, the coatingcomposition of Example 4 has a considerably higher Mc value along with amuch lower L value in both mono-coat and base coat/clear coat systems.In addition, bluetone is also improved. Thus, the dispersantcompositions of the present invention can be used to prepare pigmentcompositions which give coating composition with good jetness andbluetone compared to coating compositions of the Comparative Examples.

As a result, coating compositions of the present invention, containingthe pigment compositions and dispersant compositions described herein,have been found to provide high color performance in coatingapplications.

The foregoing description of preferred embodiments of the presentinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Modifications and variationsare possible in light of the above teachings, or may be acquired frompractice of the invention. The embodiments were chosen and described inorder to explain the principles of the invention and its practicalapplication to enable one skilled in the art to utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto, and theirequivalents.

1. A pigment composition comprising a) at least one pigment, and b) atleast one dispersant composition comprising i) at least one nonionicsurfactant which is insoluble in water and ii) at least one polymercomprising at least one salt of a carboxylic acid group which is solublein water, wherein the non-ionic surfactant is a polyalkylene oxide thatis greater than 90% capped and has a molecular weight between about 2500and 10000, and wherein the pigment is a modified carbon productcomprising a carbon product having attached at least one organic group.2. The pigment composition of claim 1, wherein the organic groupcomprises at least one ionic group, at least one ionizable group, or amixture thereof.
 3. The pigment composition of claim 1, wherein theorganic group comprises at least one anionic group.
 4. The pigmentcomposition of claim 1, wherein the organic group comprises at least onecarboxylic group, a sulfonate group, or salts thereof.
 5. The pigmentcomposition of claim 1, wherein the organic group is a carboxyphenylgroup, a sulfophenyl group, or salts thereof.
 6. The pigment compositionof claim 1, further comprising an aqueous vehicle.
 7. The pigmentcomposition of claim 6, wherein the aqueous vehicle is water.
 8. Thepigment composition of claim 1, wherein the nonionic surfactant is apolyalkylene oxide, the polymer is an ammonium salt of a copolymer ofacrylic acid and methylmethacrylate, and the pigment is a modifiedcarbon product comprising a carbon product having attached at least onesulfonate group.
 9. An aqueous coating composition comprising a) anaqueous vehicle comprising a water-based resin and an aqueous solvent,b) at least one pigment, and c) at least one dispersant compositioncomprising i) at least one nonionic surfactant which is insoluble inwater and ii) at least one polymer comprising at least one salt of acarboxylic acid group which is soluble in water, wherein the non-ionicsurfactant is a polyalkylene oxide that is greater than 90% capped andhas a molecular weight between about 2500 and 10000, and wherein thepigment is a modified carbon product comprising a carbon product havingattached at least one organic group.
 10. The aqueous coating compositionof claim 9, wherein the water-based resin is an acrylic resin, apolyurethane resin, an epoxy resin, a polyester resin, an alkyd resin,or a vinyl chloride-copolymer resin.
 11. The aqueous coating compositionof claim 9, wherein the water-based resin is an acrylic latex.
 12. Theaqueous coating composition of claim 9, wherein the aqueous solvent isgreater than 70% water.
 13. The aqueous coating composition of claim 9,wherein the aqueous solvent is greater than 85% water.
 14. The aqueouscoating composition of claim 9, wherein the organic group comprises atleast one ionic group, at least one ionizable group, or a mixturethereof.
 15. The aqueous coating composition of claim 9, wherein theorganic group comprises an anionic group.
 16. The aqueous coatingcomposition of claim 9, wherein the organic group comprises a carboxylicgroup, a sulfonate group, or salts thereof.
 17. The aqueous coatingcomposition of claim 9, wherein the organic group is a carboxyphenylgroup, a sulfophenyl group, or salts thereof.
 18. The aqueous coatingcomposition of claim 9, wherein the nonionic surfactant is apolyalkylene oxide, the polymer is an ammonium salt of a copolymer ofacrylic acid and methylmethacrylate, and the pigment is a pigment is amodified carbon product comprising a carbon product having attached atleast one sulfonate group.